The Science Underpinning Anomalous Scaling Laws of Strength and Toughness in Nanocellulose Materials

支持纳米纤维素材料强度和韧性异常缩放定律的科学

• 批准号: 1362256
• 负责人: Teng Li
• 金额: $ 40万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1362256&HistoricalAwards=false
• 关键词: Science; Underpinning; Anomalous; Scaling; Laws

The quest of materials possessing both high strength and high toughness is perpetual in advanced material design. Unfortunately, these two mechanical properties are generally mutually exclusive. For example, for metals and alloys, their toughness is usually inversely proportional to their strength. As a result, in practice, the design of strong and tough materials is inevitably a compromise. So far, a general and feasible mechanism to address the conflict of strength vs. toughness still remains elusive. This project plans to shed insight on a possible strategy resolving the conflict of strength vs. toughness by investigating the fundamental science of the anomalous but desirable scaling law of mechanical properties of cellulose nanopaper: both its strength and toughness increase as the cellulose fiber size decreases. These unique features combined with the intrinsic biodegradability, low-cost and scalable manufacturing of cellulose paper can have significant impact on bottom-up design of high performance materials with desirable mechanical properties. The research plan will be carried out in a systematic framework integrating multi-scale mechanics modeling and complementary experiments and consists of two thrusts. The overarching goal of Thrust 1 is to establish a quantitative understanding of the underpinning mechanism of both strong and tough cellulose nanopaper, by investigating the mechanics of cellulose molecular chains, nanofibrillated cellulose fibers and cellulose fiber network via multi-scale mechanics modeling and complementary experiments. The fundamental understanding from Thrust 1 will lay out a solid foundation that motivates and enables the research efforts in Thrust 2, which focuses on generalizing the underpinning mechanism of attaining both strength and toughness to guide the exploration of a class of strong and tough materials with other highly desirable multi-functionalities. Interdisciplinary graduate student training will enable to access world-class imaging and metrology facilities at NIST, and to learn from the vast expertise and state-of the-art technology from a world leading paper company. Outreach activities will be conducted via iMechanica.org, the largest international online community of mechanics with 50,000+ registered users.

在先进的材料设计中，对同时具有高强度和高韧性的材料的追求是永恒的。不幸的是，这两种机械性能通常是相互排斥的。例如，对于金属和合金，它们的韧性通常与它们的强度成反比。因此，在实践中，强韧材料的设计不可避免地是一种妥协。到目前为止，解决强度与韧性之间的冲突的普遍而可行的机制仍然难以捉摸。该项目计划通过研究纤维素纳米纸机械性能的反常但令人满意的定标规律的基础科学：随着纤维素纤维尺寸的减小，其强度和韧性都会增加，从而深入了解解决强度与韧性冲突的可能策略。这些独特的特性与纤维素纸固有的生物降解性、低成本和可扩展制造相结合，可以对具有理想机械性能的高性能材料的自下而上设计产生重大影响。该研究计划将在多尺度力学建模和补充试验相结合的系统框架内进行，包括两个推力。推力1的首要目标是通过多尺度力学建模和互补性实验研究纤维素分子链、纳米原纤化纤维和纤维素纤维网络的力学，从而建立对强韧纳米纤维纸支撑机理的定量理解。对推力1的基本理解将为推动和支持推力2的研究工作奠定坚实的基础，推力2的重点是概括兼具强度和韧性的支撑机制，以指导探索具有其他高度期望的多功能的一类强韧材料。跨学科的研究生培训将使学生能够接触到NIST的世界级成像和计量设施，并从世界领先的造纸公司学习丰富的专业知识和最先进的技术。推广活动将通过iMachica.org进行，这是拥有50,000多名注册用户的最大的国际机械师在线社区。